1. Field of the Invention
The present invention relates to a touch panel device, and more particularly to an apparatus and method for driving a touch panel device.
2. Description of the Related Art
In general, touch panel devices are considered computer peripherals that are installed on a display surface of display devices, such as cathode ray tube (CRT) devices, liquid crystal display (LCD) devices, field emission display (FED) devices, plasma display panel (PDP) devices, and electro-luminescence display (ELD) devices. As a user applies pressure onto the touch panel while looking at the display device, predetermined information is input into a computer.
FIG. 1 is a schematic diagram of touch panel device incorporated with a liquid crystal display panel according to the related art. In FIG. 1, a liquid crystal display device and a touch panel device separately include a touch panel 2, a liquid crystal display panel 4, and a backlight device 6. In addition, a computer system 12 drives the touch panel 2 via and a touch controller 10 connected to the computer system 12, wherein a flexible printed circuit film FPC 8 interconnects the touch controller 10 and the touch panel 2.
The touch panel 2 receives power supplied from the touch controller 10 to apply a coordinate signal to the touch controller 10, wherein the coordinate signal is generated when a user presses the touch panel 2 with a stylus pen or a finger. Alternatively, the computer system 12 can be superseded with a main board of a personal computer. The computer system 12 supplies drive signals and video data necessary for the display panel and, at the same time, supplies power necessary for the touch panel 2 to control the display panel and the touch panel 2.
FIG. 2 is a schematic diagram of the touch controller of FIG. 1 according to the related art. In FIG. 2, the touch controller 10 includes an analog-to-digital converter (ADC) 20 to convert an arbitrary analog voltage detected at the touch panel 2 into a digital voltage, a microcomputer 22 to respond to digital voltage values of an X-axis and a Y-axis converted by the ADC 20, and an interface integrated circuit (IC) 24 to make the microcomputer 22 compatible with the external computer system 12.
The ADC 20 converts the analog voltage value of an X-axis detected upon application of pressure to the touch panel 2 with the pen into the digital voltage value of the X-axis. Further, the ADC 20 converts the analog voltage value of a Y-axis detected upon application of pressure to the touch panel 2 with the pen into the digital voltage value of the Y-axis.
The microcomputer 22 receives the digital voltage values of the X-axis and the Y-axis converted by the ADC 20. Further, the microcomputer 22 switches the digital voltage value converted by the ADC 20 to the X-axis or the Y-coordinate. The interface IC 24 is connected between the microcomputer 22 and the computer system 12 of the liquid crystal display that has the touch panel 2 built within itself. The interface IC 24 transmits the voltage coordinate values to the computer system 12 connected to the touch panel 2, wherein the voltage value of the X-axis and the Y-axis converted by the ADC 20 is output in response to control of the microcomputer 22. The touch controller 10 converts the power supply voltage input from the computer system 12 into a power supply suitable for driving the touch panel 2 and, at the same time, supplies the coordinate signal input from the touch panel 2 to the computer system 12.
FIG. 3 is a flow chart of a method for driving a touch panel according to the related art. In FIG. 3, a microcomputer 22 (in FIG. 2) is set to be an X-axis coordinate mode in order to detect an X-axis coordinate. A potential coordinate of the set X-axis coordinate mode has a different voltage value in accordance with a location where a first electrode layer and a second electrode layer of the touch panel is pressed together to be shorted.
In step S31, the voltage value is the X-axis voltage value at the pressed point. Then, the microcomputer 22 (in FIG. 2) is converted from the set X-axis coordinate mode to a Y-axis coordinate mode in order to detect the Y-axis coordinate. A potential coordinate of the converted Y-axis coordinate mode has a different voltage value in accordance with the location where the first electrode layer and the second electrode layer of the touch panel are pressed together to be shorted.
In step S32, the voltage value is the Y-axis voltage value at the pressed point.
In step S33, the microcomputer 22 (in FIG. 2) calculates X- and Y-coordinates in use of the detected X-axis and the detected Y-axis voltages.
In step S34, the calculated X- and Y-axis coordinates are transmitted to the computer system 12 connected to the display device of the touch panel through the interface IC.
FIG. 4 is a schematic diagram of a transmitting connector and a receiving connector for interconnecting a touch controller with a computer system according to the related art. In FIG. 4, the X- and Y-axis coordinates are transmitted to the computer system 12 through a transmitting connector 26 and a receiving connector 28 connected to the interface IC 24. Accordingly, the transmitting connector 26 is connected to the receiving connector corresponding to itself among a plurality of receiving connectors 28a to 28n. However, there is only one interface IC 24 in a touch board (not shown) where the touch controller 10 is formed. Accordingly, if the user has another interface IC, another touch controller is needed, thereby resulting in low compatibility. Furthermore, there is a problem in that one touch board is required for each interface IC 24.